As steel rod exits the downstream end of a rolling line it is typically formed into annular coils each constituted by a multiplicity of turns. Such coiling is typically done in a Garrett-type installation as described in Austrian patent 393,806 by feeding the still very hot rod through a laying pipe into an upwardly open annular basket delimiting an annular space in turn defined by an inner and an outer annular array of parallel rods. The basket may be rotated to ensure that the turns lie neatly atop one another, with the coil forming from the bottom up. The entire coil-forming operation can take place under water to cool and stiffen the rod as it is coiled. Once a coil is formed of the requisite size measured along the axis, the infeed of rod is cut and the floor is raised so that an appropriate grab can carry off the finished coil.
When the rod is fairly thick, that is less than 40 mm in diameter, it can be formed into fairly stable coils that can be handled, although it takes some care to prevent the coils from spilling apart and becoming unusable. When thinner rod is wound the top several turns are normally so loose that they pose a hazard and must be cut away and discarded. Such trimming of the coil is a difficult and dangerous operation that wastes product. Even trimmed, such a coil is extremely difficult to handle. Normally there is a tradeoff between cooling the coil enough that the rod stiffens to make the coil stable, and leaving it hot enough so that for subsequent operations, e.g. forming into concrete reinforcement bar, the rod remains relatively soft so that the coil is unstable.